One of the most common flowering plants, foxglove, could soon be used to stop the spread of breast cancer, say scientists at Johns Hopkins University, Baltimore.
The scientists have discovered that a drug based on foxglove (Digitalis), which produces distinctive tall spires of pink tubular bells in the summer, can dramatically slow the migration of malignant cells to other parts of the body.
The research reveals that digoxin, a long-established drug based on chemicals found in foxglove, can block the production of a protein called HIF-1, which has been implicated in the spread of breast tumours.
Digoxin has been used for decades to treat conditions such as congestive heart failure and irregular heartbeats.
The latest discovery suggests the cheap and easily available medicine could also be deployed in the fight against cancer.
Earlier this year the same team found foxglove could reduce the spread of prostate cancer in men by around 24%.
Research leader, Dr. Gregg Semenza, from the Institute for Cell Engineering at the university said: “This is really exciting.”
“Our findings warrant clinical trials to determine if the doses (used in animal studies) are enough to sufficiently block HIF-1 and slow breast cancer growth and spread.”
Foxglove was one of the first plants to be used for the development of a pharmaceutical medicine.
In 1785, country doctor William Withering noticed a remarkable improvement in a patient with congestive heart failure after they took a traditional herbal remedy made from the plant.
William Withering identified that the active ingredient was a substance called digitalis and wrote about his findings more than 200 years ago in a book entitled “An account of the foxglove and some of its medical uses”.
GlaxoSmithKline eventually turned it into a tablet called digoxin, used for heart failure as well as atrial fibrillation, an abnormal heart rhythm.
In recent months, new evidence has emerged that the traditional remedy could also play a vital role in treating cancer.
In April this year, the Johns Hopkins research team reported the results of a study involving 47,000 men in the journal Cancer Discovery.
These showed the drug appeared to stop the growth of prostate cancer in nearly one in four men.
But researchers warned this did not yet provide proof that digoxin was responsible for the benefits and warned against the drug, which can have side-effects such as nausea, headache and breast enlargement in men, being given to healthy people to prevent tumours.
Laboratory tests show digoxin appears to hinder the production of HIF-1, a protein that controls the genes which allow cancer cells to survive in low-oxygen environments, such as deep inside a solid tumour.
Experiments have also revealed that in women with breast cancer, an increase in HIF-1 levels is closely linked to metastasis – the spread of tumour cells – and a reduced likelihood of survival.
To see how the HIF-1 protein behaved when exposed to digoxin, researchers transplanted human breast cancer cells into mice and, two weeks later, gave them daily injections of either the drug itself or saline.
The results showed those given digoxin had fewer cancer cells spread to the lungs – one of the major sites that breast tumours migrate to – and tumours that had spread were smaller than in the saline group.
The findings could be even more significant because the research team found evidence that cancer cells start to spread from the breast to the lung much earlier than was previously thought.
This could mean that if further trials confirm the benefits of the drug, it’s possible it could be routinely used in women with aggressive tumours to try and reduce the risk of them spreading.